Index: Application/Ringtoets/test/Application.Ringtoets.Storage.Test/IntegrationTests/StorageSqLiteIntegrationTest.cs
===================================================================
diff -u -r31012b85637f7fcf6b28f498fc996edcda2eb505 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Application/Ringtoets/test/Application.Ringtoets.Storage.Test/IntegrationTests/StorageSqLiteIntegrationTest.cs	(.../StorageSqLiteIntegrationTest.cs)	(revision 31012b85637f7fcf6b28f498fc996edcda2eb505)
+++ Application/Ringtoets/test/Application.Ringtoets.Storage.Test/IntegrationTests/StorageSqLiteIntegrationTest.cs	(.../StorageSqLiteIntegrationTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -535,8 +535,8 @@
             CollectionAssert.AreEqual(expectedReferenceLine.Points, actualReferenceLine.Points);
         }
 
-        private static void AssertStochasticSoilModels(ObservableCollectionWithSourcePath<StochasticSoilModel> expectedModels,
-                                                       ObservableCollectionWithSourcePath<StochasticSoilModel> actualModels)
+        private static void AssertStochasticSoilModels(ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel> expectedModels,
+                                                       ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel> actualModels)
         {
             // Precondition:
             Assert.Less(0, actualModels.Count);
@@ -605,8 +605,8 @@
             }
         }
 
-        private static void AssertSurfaceLines(ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine> expectedSurfaceLines,
-                                               ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine> actualSurfaceLines)
+        private static void AssertSurfaceLines(ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine> expectedSurfaceLines,
+                                               ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine> actualSurfaceLines)
         {
             // Precondition:
             Assert.Greater(expectedSurfaceLines.Count, 0);
Index: Core/Common/src/Core.Common.Base/Core.Common.Base.csproj
===================================================================
diff -u -r974fb1eadbd8a630c7a992648ad42ac85ec205b1 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Core/Common/src/Core.Common.Base/Core.Common.Base.csproj	(.../Core.Common.Base.csproj)	(revision 974fb1eadbd8a630c7a992648ad42ac85ec205b1)
+++ Core/Common/src/Core.Common.Base/Core.Common.Base.csproj	(.../Core.Common.Base.csproj)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -105,7 +105,7 @@
     <Compile Include="IO\OnProgressChanged.cs" />
     <Compile Include="Observer.cs" />
     <Compile Include="RecursiveObserver.cs" />
-    <Compile Include="ObservableCollectionWithSourcePath.cs" />
+    <Compile Include="ObservableUniqueItemCollectionWithSourcePath.cs" />
     <Compile Include="Storage\StorageException.cs" />
     <Compile Include="Storage\StorageValidationException.cs" />
     <Compile Include="Storage\CouldNotConnectException.cs" />
Fisheye: Tag 66b07e7599319ea71ff109d8303f74a4a2e5f71c refers to a dead (removed) revision in file `Core/Common/src/Core.Common.Base/ObservableCollectionWithSourcePath.cs'.
Fisheye: No comparison available.  Pass `N' to diff?
Index: Core/Common/src/Core.Common.Base/ObservableUniqueItemCollectionWithSourcePath.cs
===================================================================
diff -u
--- Core/Common/src/Core.Common.Base/ObservableUniqueItemCollectionWithSourcePath.cs	(revision 0)
+++ Core/Common/src/Core.Common.Base/ObservableUniqueItemCollectionWithSourcePath.cs	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -0,0 +1,188 @@
+// Copyright (C) Stichting Deltares 2016. All rights reserved.
+//
+// This file is part of Ringtoets.
+//
+// Ringtoets is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using System;
+using System.Collections;
+using System.Collections.Generic;
+using System.Linq;
+using Core.Common.Utils;
+
+namespace Core.Common.Base
+{
+    /// <summary>
+    /// A collection to store unique elements based on their feature and the source path
+    /// they were imported from.
+    /// </summary>
+    /// <typeparam name="TObject">The type of elements in the collection.</typeparam>
+    public class ObservableUniqueItemCollectionWithSourcePath<TObject> : Observable, IEnumerable<TObject>
+        where TObject : class
+    {
+        private readonly List<TObject> collection = new List<TObject>();
+
+        /// <summary>
+        /// Gets the element at index <paramref name="i"/> in the collection.
+        /// </summary>
+        /// <param name="i">The index.</param>
+        /// <returns>The element at index <paramref name="i"/> in the collection.</returns>
+        /// <exception cref="ArgumentOutOfRangeException">Thrown when <paramref name="i"/> is not 
+        /// between [0, <see cref="Count"/>)</exception>
+        public TObject this[int i]
+        {
+            get
+            {
+                return collection[i];
+            }
+        }
+
+        /// <summary>
+        /// Gets the amount of items stored in the collection.
+        /// </summary>
+        public int Count
+        {
+            get
+            {
+                return collection.Count;
+            }
+        }
+
+        /// <summary>
+        /// Gets the last known file path from which the elements were imported.
+        /// </summary>
+        /// <returns>The path where the elements originate
+        /// from, or <c>null</c> if the collection is cleared.</returns>
+        public string SourcePath { get; private set; }
+
+        /// <summary>
+        /// Removes the first occurrence of <paramref name="item"/> in the collection.
+        /// </summary>
+        /// <param name="item">The item of type <see cref="TObject"/> to be removed.</param>
+        /// <returns><c>True</c> if the <paramref name="item"/> was successfully removed from the collection;
+        /// <c>False</c> if otherwise or if the <paramref name="item"/> was not found in the collection. </returns>
+        public bool Remove(TObject item)
+        {
+            bool remove = collection.Remove(item);
+            if (remove && Count == 0)
+            {
+                SourcePath = null;
+            }
+            return remove;
+        }
+
+        /// <summary>
+        /// Clears the imported items in the collection and the <see cref="SourcePath"/>.
+        /// </summary>
+        public void Clear()
+        {
+            SourcePath = null;
+            collection.Clear();
+        }
+
+        /// <summary>
+        /// Adds all elements originating from a source file.
+        /// </summary>
+        /// <param name="items">The elements to add</param>
+        /// <param name="filePath">The path to the source file.</param>
+        /// <exception cref="ArgumentNullException">Thrown when any input argument is <c>null</c>.</exception>
+        /// <exception cref="ArgumentException">Thrown when:
+        /// <list type="bullet">
+        /// <item><paramref name="items"/> contains <c>null</c>.</item>
+        /// <item><paramref name="filePath"/> is not a valid file path.</item>
+        /// <item>an element in <paramref name="items"/> is invalid.</item>
+        /// </list>
+        /// </exception>
+        public void AddRange(IEnumerable<TObject> items, string filePath)
+        {
+            if (items == null)
+            {
+                throw new ArgumentNullException(nameof(items));
+            }
+            if (filePath == null)
+            {
+                throw new ArgumentNullException(nameof(filePath));
+            }
+            if (!IOUtils.IsValidFilePath(filePath))
+            {
+                throw new ArgumentException($"'{filePath}' is not a valid filepath.", nameof(filePath));
+            }
+            InternalValidateItems(items);
+
+            SourcePath = filePath;
+            collection.AddRange(items);
+        }
+
+        private void InternalValidateItems(IEnumerable<TObject> items)
+        {
+            if (items.Contains(null))
+            {
+                throw new ArgumentException("Collection cannot contain null.", nameof(items));
+            }
+            ValidateItems(items);
+        }
+
+        /// <summary>
+        /// Perform additional validations over <paramref name="items"/>.
+        /// </summary>
+        /// <param name="items">The items to validate.</param>
+        /// <exception cref="ArgumentException">Throw an exception when validation fails.</exception>
+        protected virtual void ValidateItems(IEnumerable<TObject> items) {}
+
+        /// <summary>
+        /// Validates the items of an <see cref="IEnumerable{TObject}"/> based on their names.
+        /// </summary>
+        /// <typeparam name="TFeature">The feautre that needs to be validated on.</typeparam>
+        /// <param name="items">The collection that needs to be validated.</param>
+        /// <param name="getUniqueFeature">The feature of the items contained by the collection 
+        /// that needs to be validated on.</param>
+        /// <param name="typeDescriptor">The description of the item which was validated.</param>
+        /// <param name="featureDescription">The description of the feature which was validated on.</param>
+        /// <exception cref="ArgumentNullException">Thrown when any parameters are <c>null</c>.</exception>
+        /// <exception cref="ArgumentException">Thrown when a duplicate item was found.</exception>
+        protected void ValidateListOnDuplicateFeature<TFeature>(IEnumerable<TObject> items,
+                                                                Func<TObject, TFeature> getUniqueFeature,
+                                                                string typeDescriptor,
+                                                                string featureDescription)
+        {
+            IEnumerable<IGrouping<TFeature, TObject>> duplicateItems =
+                items.GroupBy(getUniqueFeature)
+                     .Where(group => group.Count() > 1);
+
+            if (duplicateItems.Any())
+            {
+                var duplicateFeatures = string.Join(", ", duplicateItems.Select(group => group.First()));
+                string exceptionMessage = string.Format("{0} moeten een unieke {1} hebben. Gevonden dubbele elementen: {2}.",
+                                                        typeDescriptor,
+                                                        featureDescription,
+                                                        duplicateFeatures);
+                throw new ArgumentException(exceptionMessage);
+            }
+        }
+
+        public IEnumerator<TObject> GetEnumerator()
+        {
+            return collection.GetEnumerator();
+        }
+
+        IEnumerator IEnumerable.GetEnumerator()
+        {
+            return GetEnumerator();
+        }
+    }
+}
\ No newline at end of file
Index: Core/Common/test/Core.Common.Base.Test/Core.Common.Base.Test.csproj
===================================================================
diff -u -r974fb1eadbd8a630c7a992648ad42ac85ec205b1 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Core/Common/test/Core.Common.Base.Test/Core.Common.Base.Test.csproj	(.../Core.Common.Base.Test.csproj)	(revision 974fb1eadbd8a630c7a992648ad42ac85ec205b1)
+++ Core/Common/test/Core.Common.Base.Test/Core.Common.Base.Test.csproj	(.../Core.Common.Base.Test.csproj)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -102,7 +102,7 @@
     <Compile Include="ObservableListTest.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="Service\FileImportActivityTest.cs" />
-    <Compile Include="ObservableCollectionWithSourcePathTest.cs" />
+    <Compile Include="ObservableUniqueItemCollectionWithSourcePathTest.cs" />
     <Compile Include="Storage\StorageExceptionTest.cs" />
     <Compile Include="Storage\StorageValidationExceptionTest.cs" />
     <Compile Include="Storage\CouldNotConnectExceptionTest.cs" />
Fisheye: Tag 66b07e7599319ea71ff109d8303f74a4a2e5f71c refers to a dead (removed) revision in file `Core/Common/test/Core.Common.Base.Test/ObservableCollectionWithSourcePathTest.cs'.
Fisheye: No comparison available.  Pass `N' to diff?
Index: Core/Common/test/Core.Common.Base.Test/ObservableUniqueItemCollectionWithSourcePathTest.cs
===================================================================
diff -u
--- Core/Common/test/Core.Common.Base.Test/ObservableUniqueItemCollectionWithSourcePathTest.cs	(revision 0)
+++ Core/Common/test/Core.Common.Base.Test/ObservableUniqueItemCollectionWithSourcePathTest.cs	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -0,0 +1,417 @@
+// Copyright (C) Stichting Deltares 2016. All rights reserved.
+//
+// This file is part of Ringtoets.
+//
+// Ringtoets is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+//
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using System;
+using System.Linq;
+using Core.Common.TestUtil;
+using NUnit.Framework;
+using Rhino.Mocks;
+
+namespace Core.Common.Base.Test
+{
+    [TestFixture]
+    public class ObservableUniqueItemCollectionWithSourcePathTest
+    {
+        [Test]
+        public void DefaultConstructor_ReturnObservableCollectionWithSourcePath()
+        {
+            // Call
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+
+            // Assert
+            Assert.IsInstanceOf<Observable>(collection);
+            Assert.IsNull(collection.SourcePath);
+            Assert.AreEqual(0, collection.Count);
+            CollectionAssert.IsEmpty(collection);
+        }
+
+        [Test]
+        public void AddRange_ItemsNull_ThrowArgumentNullException()
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+
+            // Call
+            TestDelegate call = () => collection.AddRange(null, "path");
+
+            // Assert
+            string paramName = Assert.Throws<ArgumentNullException>(call).ParamName;
+            Assert.AreEqual("items", paramName);
+        }
+
+        [Test]
+        public void AddRange_ItemsHasNullElement_ThrowArgumentException()
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            var items = new[]
+            {
+                new object(),
+                null,
+                new object()
+            };
+
+            // Call
+            TestDelegate call = () => collection.AddRange(items, "path");
+
+            // Assert
+            string message = "Collection cannot contain null.";
+            string paramName = TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(call, message).ParamName;
+            Assert.AreEqual("items", paramName);
+        }
+
+        [Test]
+        public void AddRange_FilePathNull_ThrowArgumentNullException()
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+
+            // Call
+            TestDelegate call = () => collection.AddRange(Enumerable.Empty<object>(), null);
+
+            // Assert
+            string paramName = Assert.Throws<ArgumentNullException>(call).ParamName;
+            Assert.AreEqual("filePath", paramName);
+        }
+
+        [Test]
+        public void AddRange_NotAnActualFilePath_ThrowArgumentNull()
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+
+            const string invalidFilePath = @"            ";
+
+            // Call
+            TestDelegate call = () => collection.AddRange(Enumerable.Empty<object>(), invalidFilePath);
+
+            // Assert
+            string message = $"'{invalidFilePath}' is not a valid filepath.";
+            string paramName = TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(call, message).ParamName;
+            Assert.AreEqual("filePath", paramName);
+        }
+
+        [Test]
+        public void AddRange_AddNewItem_CollectionContainsItem()
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            var item = new object();
+
+            // Call 
+            const string filePath = "some/file/path";
+            collection.AddRange(new[]
+            {
+                item
+            }, filePath);
+
+            // Assert
+            CollectionAssert.Contains(collection, item);
+            Assert.AreEqual(filePath, collection.SourcePath);
+        }
+
+        [Test]
+        public void AddRange_AddingNewItems_CollectionContainsExpectedElements()
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            var expectedCollection = new[]
+            {
+                new object(),
+                new object(),
+                new object(),
+                new object()
+            };
+
+            const string filePath = "some/file/path";
+
+            // Call
+            collection.AddRange(expectedCollection, filePath);
+
+            // Assert
+            CollectionAssert.AreEqual(expectedCollection, collection);
+            Assert.AreEqual(filePath, collection.SourcePath);
+        }
+
+        [Test]
+        public void Count_CollectionFilledWithElements_ReturnsExpectedNumberOfElements()
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            collection.AddRange(new[]
+            {
+                new object(),
+                new object(),
+                new object(),
+                new object()
+            }, "path");
+
+            // Call
+            int nrOfElements = collection.Count;
+
+            // Assert
+            Assert.AreEqual(4, nrOfElements);
+        }
+
+        [Test]
+        [TestCase(-1)]
+        [TestCase(0)]
+        public void Indexer_GetItemAtIndexOutOfRange_ThrowsArgumentOutOfRangeException(int invalidIndex)
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+
+            // Call
+            TestDelegate call = () =>
+            {
+                object item = collection[invalidIndex];
+            };
+
+            // Assert
+            Assert.Throws<ArgumentOutOfRangeException>(call);
+        }
+
+        [Test]
+        public void Indexer_GetElementAtIndex_ReturnsExpectedElement()
+        {
+            // Setup
+            var elementToRetrieve = new object();
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            collection.AddRange(new[]
+            {
+                new object(),
+                new object(),
+                new object(),
+                new object(),
+                elementToRetrieve
+            }, "path");
+
+            // Call
+            object retrievedElement = collection[4];
+
+            // Assert
+            Assert.AreSame(elementToRetrieve, retrievedElement);
+        }
+
+        [Test]
+        public void Remove_ElementNotInList_ReturnsFalse()
+        {
+            // Setup
+            var element = new object();
+
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            var expectedCollection = new[]
+            {
+                new object(),
+                new object(),
+                new object(),
+                new object()
+            };
+
+            collection.AddRange(expectedCollection, "path");
+
+            // Call
+            bool removeSuccessful = collection.Remove(element);
+
+            // Assert
+            Assert.IsFalse(removeSuccessful);
+            CollectionAssert.AreEqual(expectedCollection, collection);
+        }
+
+        [Test]
+        public void Remove_ElementInCollection_ReturnsTrue()
+        {
+            // Setup
+            var elementToBeRemoved = new object();
+
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            var expectedCollections = new[]
+            {
+                new object(),
+                new object(),
+                new object(),
+                new object()
+            };
+
+            collection.AddRange(expectedCollections.Concat(new[]
+            {
+                elementToBeRemoved
+            }), "path");
+
+            // Call
+            bool removeSuccessful = collection.Remove(elementToBeRemoved);
+
+            // Assert
+            Assert.IsTrue(removeSuccessful);
+            CollectionAssert.AreEqual(expectedCollections, collection);
+        }
+
+        [Test]
+        public void Remove_ElementToRemoveMultiplesInCollection_ReturnsTrueAndRemovesFirstOccurence()
+        {
+            // Setup
+            var elementToBeRemoved = new object();
+
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            var removeElementCollection = new[]
+            {
+                elementToBeRemoved
+            };
+            var expectedCollection = new[]
+            {
+                new object(),
+                new object(),
+                new object(),
+                new object(),
+                elementToBeRemoved
+            };
+
+            collection.AddRange(removeElementCollection.Concat(expectedCollection), "path");
+
+            // Call
+            bool removeSuccessful = collection.Remove(elementToBeRemoved);
+
+            // Assert
+            Assert.IsTrue(removeSuccessful);
+            CollectionAssert.AreEqual(expectedCollection, collection);
+        }
+
+        [Test]
+        public void Remove_RemoveLastElement_ReturnsTrueAndClearSourcePath()
+        {
+            // Setup
+            var elementToBeRemoved = new object();
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            collection.AddRange(new[]
+            {
+                elementToBeRemoved
+            }, "path");
+
+            // Precondition
+            Assert.IsNotNull(collection.SourcePath);
+
+            // Call
+            bool removeSuccesful = collection.Remove(elementToBeRemoved);
+
+            // Assert
+            Assert.IsTrue(removeSuccesful);
+            Assert.IsNull(collection.SourcePath);
+        }
+
+        [Test]
+        public void Clear_CollectionFullyDefined_ClearsSourcePathAndCollection()
+        {
+            // Setup
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            var expectedObjectCollection = new[]
+            {
+                new object(),
+                new object(),
+                new object(),
+                new object()
+            };
+
+            collection.AddRange(expectedObjectCollection, "path");
+
+            // Call
+            collection.Clear();
+
+            // Assert
+            Assert.IsNull(collection.SourcePath);
+            Assert.AreEqual(0, collection.Count);
+            CollectionAssert.IsEmpty(collection);
+        }
+
+        [Test]
+        public void NotifyObservers_WithObserverAttached_ObserverIsNotified()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var observer = mocks.StrictMock<IObserver>();
+            observer.Expect(o => o.UpdateObserver()); // Expect to be called once
+            mocks.ReplayAll();
+
+            var observableCollection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            observableCollection.Attach(observer);
+
+            // Call
+            observableCollection.NotifyObservers();
+
+            // Assert
+            mocks.VerifyAll();
+        }
+
+        [Test]
+        public void NotifyObserver_AttachedObserverDetachedAgain_ObserverNoLongerNotified()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var observer = mocks.StrictMock<IObserver>();
+            mocks.ReplayAll();
+
+            var observableCollection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+            observableCollection.Attach(observer);
+            observableCollection.Detach(observer);
+
+            // Call
+            observableCollection.NotifyObservers();
+
+            // Assert
+            mocks.VerifyAll(); // Expect no calls on 'observer'
+        }
+
+        [Test]
+        public void NotifyObservers_MultipleObserversDetachingOrAttachingOthers_NoUpdatesForAttachedAndDetachedObservers()
+        {
+            // Setup
+            var mocks = new MockRepository();
+            var observableCollection = new ObservableUniqueItemCollectionWithSourcePath<object>();
+
+            var observer1 = mocks.Stub<IObserver>();
+            var observer2 = mocks.Stub<IObserver>();
+            var observer3 = mocks.Stub<IObserver>();
+            var observer4 = mocks.Stub<IObserver>();
+            var observer5 = mocks.Stub<IObserver>();
+            var observer6 = mocks.Stub<IObserver>();
+
+            observableCollection.Attach(observer1);
+            observableCollection.Attach(observer2);
+            observableCollection.Attach(observer3);
+            observableCollection.Attach(observer4);
+            observableCollection.Attach(observer6);
+
+            observer1.Expect(o => o.UpdateObserver());
+            observer2.Expect(o => o.UpdateObserver()).Do((Action) (() => observableCollection.Detach(observer3)));
+            observer3.Expect(o => o.UpdateObserver()).Repeat.Never(); // A detached observer should no longer be updated
+            observer4.Expect(o => o.UpdateObserver()).Do((Action) (() => observableCollection.Attach(observer5)));
+            observer5.Expect(o => o.UpdateObserver()).Repeat.Never(); // An attached observer should not be updated too
+            observer6.Expect(o => o.UpdateObserver());
+
+            mocks.ReplayAll();
+
+            // Call
+            observableCollection.NotifyObservers();
+
+            // Assert
+            mocks.VerifyAll();
+        }
+    }
+}
\ No newline at end of file
Index: Ringtoets/Piping/src/Ringtoets.Piping.Data/RingtoetsPipingSurfaceLineCollection.cs
===================================================================
diff -u -r393f18543bc78061b83f61fce09ca094d8fb1a05 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/src/Ringtoets.Piping.Data/RingtoetsPipingSurfaceLineCollection.cs	(.../RingtoetsPipingSurfaceLineCollection.cs)	(revision 393f18543bc78061b83f61fce09ca094d8fb1a05)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Data/RingtoetsPipingSurfaceLineCollection.cs	(.../RingtoetsPipingSurfaceLineCollection.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -19,36 +19,20 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
-using System;
 using System.Collections.Generic;
-using System.Linq;
 using Core.Common.Base;
-using Ringtoets.Piping.Data.Properties;
 using Ringtoets.Piping.Primitives;
 
 namespace Ringtoets.Piping.Data
 {
     /// <summary>
     /// Collection to store <see cref="RingtoetsPipingSurfaceLine"/>.
     /// </summary>
-    public class RingtoetsPipingSurfaceLineCollection : ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine>
+    public class RingtoetsPipingSurfaceLineCollection : ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine>
     {
-        private const string separator = ", ";
-
         protected override void ValidateItems(IEnumerable<RingtoetsPipingSurfaceLine> items)
         {
-            IEnumerable<IGrouping<string, RingtoetsPipingSurfaceLine>> duplicateItems =
-                items.GroupBy(item => item.Name)
-                     .Where(group => group.Count() > 1);
-
-            if (duplicateItems.Any())
-            {
-                var names = string.Join(separator, duplicateItems.Select(group => group.First()));
-                string message = string.Format(
-                    Resources.RingtoetsPipingSurfaceLineCollection_ValidateItems_RingtoetsPipingSurfaceLine_require_unique_names_found_duplicate_items_0_,
-                    names);
-                throw new ArgumentException(message);
-            }
+            ValidateListOnDuplicateFeature(items, line => line.Name, "Profielschematisaties", "naam");
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/Piping/src/Ringtoets.Piping.Data/StochasticSoilModelCollection.cs
===================================================================
diff -u -r8eb717ca45b6518cccfef85e481e0da52ce1df4e -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/src/Ringtoets.Piping.Data/StochasticSoilModelCollection.cs	(.../StochasticSoilModelCollection.cs)	(revision 8eb717ca45b6518cccfef85e481e0da52ce1df4e)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Data/StochasticSoilModelCollection.cs	(.../StochasticSoilModelCollection.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -19,26 +19,19 @@
 // Stichting Deltares and remain full property of Stichting Deltares at all times.
 // All rights reserved.
 
-using System;
 using System.Collections.Generic;
-using System.Linq;
 using Core.Common.Base;
 
 namespace Ringtoets.Piping.Data
 {
     /// <summary>
     /// A collection of <see cref="StochasticSoilModel"/>.
     /// </summary>
-    public class StochasticSoilModelCollection : ObservableCollectionWithSourcePath<StochasticSoilModel>
+    public class StochasticSoilModelCollection : ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel>
     {
         protected override void ValidateItems(IEnumerable<StochasticSoilModel> items)
         {
-            IEnumerable<IGrouping<string, StochasticSoilModel>> duplicates = items.GroupBy(m => m.Name).Where(g => g.Count() > 1);
-            if(duplicates.Any())
-            {
-                var names = string.Join(", ", duplicates.Select(g => g.First()));
-                throw new ArgumentException($@"Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele namen: {names}.");
-            }
+            ValidateListOnDuplicateFeature(items, model => model.Name, "Ondergrondmodellen", "naam");
         }
     }
 }
\ No newline at end of file
Index: Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/RingtoetsPipingSurfaceLineCollectionProperties.cs
===================================================================
diff -u -r922e186b7941457f71de9b4909fa2490f36a1c63 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/RingtoetsPipingSurfaceLineCollectionProperties.cs	(.../RingtoetsPipingSurfaceLineCollectionProperties.cs)	(revision 922e186b7941457f71de9b4909fa2490f36a1c63)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/RingtoetsPipingSurfaceLineCollectionProperties.cs	(.../RingtoetsPipingSurfaceLineCollectionProperties.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -30,17 +30,17 @@
 namespace Ringtoets.Piping.Forms.PropertyClasses
 {
     /// <summary>
-    /// ViewModel of <see cref="ObservableCollectionWithSourcePath{T}"/> of <see cref="RingtoetsPipingSurfaceLine"/> for properties panel.
+    /// ViewModel of <see cref="ObservableUniqueItemCollectionWithSourcePath{TObject}"/> of <see cref="RingtoetsPipingSurfaceLine"/> for properties panel.
     /// </summary>
-    public class RingtoetsPipingSurfaceLineCollectionProperties : ObjectProperties<ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine>>
+    public class RingtoetsPipingSurfaceLineCollectionProperties : ObjectProperties<ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine>>
     {
         /// <summary>
         /// Creates a new instance of <see cref="RingtoetsPipingSurfaceLineCollectionProperties"/>.
         /// </summary>
         /// <param name="collection">The collection for which the properties are shown.</param>
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="collection"/>
         /// is <c>null</c>.</exception>
-        public RingtoetsPipingSurfaceLineCollectionProperties(ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine> collection)
+        public RingtoetsPipingSurfaceLineCollectionProperties(ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine> collection)
         {
             if (collection == null)
             {
Index: Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/StochasticSoilModelCollectionProperties.cs
===================================================================
diff -u -r922e186b7941457f71de9b4909fa2490f36a1c63 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/StochasticSoilModelCollectionProperties.cs	(.../StochasticSoilModelCollectionProperties.cs)	(revision 922e186b7941457f71de9b4909fa2490f36a1c63)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Forms/PropertyClasses/StochasticSoilModelCollectionProperties.cs	(.../StochasticSoilModelCollectionProperties.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -30,17 +30,17 @@
 namespace Ringtoets.Piping.Forms.PropertyClasses
 {
     /// <summary>
-    /// ViewModel of <see cref="ObservableCollectionWithSourcePath{T}"/> of <see cref="StochasticSoilModel"/> for properties panel.
+    /// ViewModel of <see cref="ObservableUniqueItemCollectionWithSourcePath{TObject}"/> of <see cref="StochasticSoilModel"/> for properties panel.
     /// </summary>
-    public class StochasticSoilModelCollectionProperties : ObjectProperties<ObservableCollectionWithSourcePath<StochasticSoilModel>>
+    public class StochasticSoilModelCollectionProperties : ObjectProperties<ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel>>
     {
         /// <summary>
         /// Creates a new instance of <see cref="StochasticSoilModelCollectionProperties"/>.
         /// </summary>
         /// <param name="collection">The collection for which the properties are shown.</param>
         /// <exception cref="ArgumentNullException">Thrown when <paramref name="collection"/>
         /// is <c>null</c>.</exception>
-        public StochasticSoilModelCollectionProperties(ObservableCollectionWithSourcePath<StochasticSoilModel> collection)
+        public StochasticSoilModelCollectionProperties(ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel> collection)
         {
             if (collection == null)
             {
Index: Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs
===================================================================
diff -u -r31012b85637f7fcf6b28f498fc996edcda2eb505 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs	(.../PipingFailureMechanismView.cs)	(revision 31012b85637f7fcf6b28f498fc996edcda2eb505)
+++ Ringtoets/Piping/src/Ringtoets.Piping.Forms/Views/PipingFailureMechanismView.cs	(.../PipingFailureMechanismView.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -197,8 +197,8 @@
         {
             ReferenceLine referenceLine = data.Parent.ReferenceLine;
             IEnumerable<FailureMechanismSection> failureMechanismSections = data.WrappedData.Sections;
-            ObservableCollectionWithSourcePath<StochasticSoilModel> stochasticSoilModels = data.WrappedData.StochasticSoilModels;
-            ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine> ringtoetsPipingSurfaceLines = data.WrappedData.SurfaceLines;
+            ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel> stochasticSoilModels = data.WrappedData.StochasticSoilModels;
+            ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine> ringtoetsPipingSurfaceLines = data.WrappedData.SurfaceLines;
             HydraulicBoundaryDatabase hydraulicBoundaryDatabase = data.Parent.HydraulicBoundaryDatabase;
             IEnumerable<PipingCalculationScenario> calculations =
                 data.WrappedData.CalculationsGroup.GetCalculations().Cast<PipingCalculationScenario>();
Index: Ringtoets/Piping/src/Ringtoets.Piping.IO/Importers/IStochasticSoilModelUpdateModelStrategy.cs
===================================================================
diff -u -re1a8e98d60853beefbdb8c84e70f14165680ad7b -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/src/Ringtoets.Piping.IO/Importers/IStochasticSoilModelUpdateModelStrategy.cs	(.../IStochasticSoilModelUpdateModelStrategy.cs)	(revision e1a8e98d60853beefbdb8c84e70f14165680ad7b)
+++ Ringtoets/Piping/src/Ringtoets.Piping.IO/Importers/IStochasticSoilModelUpdateModelStrategy.cs	(.../IStochasticSoilModelUpdateModelStrategy.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -35,7 +35,7 @@
         /// <summary>
         /// Adds the imported data to the <paramref name="targetCollection"/>.
         /// </summary>
-        /// <param name="targetCollection">The <see cref="ObservableCollectionWithSourcePath{StochasticSoilModel}"/> to which the imported data
+        /// <param name="targetCollection">The <see cref="ObservableUniqueItemCollectionWithSourcePath{TObject}"/> to which the imported data
         /// is added.</param>
         /// <param name="readStochasticSoilModels">The stochastic soil models which were imported.</param>
         /// <param name="sourceFilePath">The path to the source file from which the soil models were imported.</param>
Index: Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/RingtoetsPipingSurfaceLineCollectionTest.cs
===================================================================
diff -u -r92549be285a5082435e9625732cf33ff50cd60b9 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/RingtoetsPipingSurfaceLineCollectionTest.cs	(.../RingtoetsPipingSurfaceLineCollectionTest.cs)	(revision 92549be285a5082435e9625732cf33ff50cd60b9)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/RingtoetsPipingSurfaceLineCollectionTest.cs	(.../RingtoetsPipingSurfaceLineCollectionTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -37,7 +37,7 @@
             var collection = new RingtoetsPipingSurfaceLineCollection();
 
             // Assert
-            Assert.IsInstanceOf<ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine>>(collection);
+            Assert.IsInstanceOf<ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine>>(collection);
         }
 
         [Test]
@@ -90,7 +90,7 @@
             TestDelegate call = () => collection.AddRange(surfaceLinesToAdd, "path");
 
             // Assert
-            string message = $"Profielschematisaties moeten een unieke naam hebben. Gevonden dubbele namen: {duplicateName}.";
+            string message = $"Profielschematisaties moeten een unieke naam hebben. Gevonden dubbele elementen: {duplicateName}.";
             TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(call, message);
         }
 
@@ -126,7 +126,7 @@
             TestDelegate call = () => collection.AddRange(surfaceLinesToAdd, "path");
 
             // Assert
-            string message = $"Profielschematisaties moeten een unieke naam hebben. Gevonden dubbele namen: {duplicateNameOne}, {duplicateNameTwo}.";
+            string message = $"Profielschematisaties moeten een unieke naam hebben. Gevonden dubbele elementen: {duplicateNameOne}, {duplicateNameTwo}.";
             TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(call, message);
         }
     }
Index: Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/StochasticSoilModelCollectionTest.cs
===================================================================
diff -u -r92549be285a5082435e9625732cf33ff50cd60b9 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/StochasticSoilModelCollectionTest.cs	(.../StochasticSoilModelCollectionTest.cs)	(revision 92549be285a5082435e9625732cf33ff50cd60b9)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Data.Test/StochasticSoilModelCollectionTest.cs	(.../StochasticSoilModelCollectionTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -36,7 +36,7 @@
             var collection = new StochasticSoilModelCollection();
 
             // Assert
-            Assert.IsInstanceOf<ObservableCollectionWithSourcePath<StochasticSoilModel>>(collection);
+            Assert.IsInstanceOf<ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel>>(collection);
         }
 
         [Test]
@@ -76,7 +76,7 @@
             TestDelegate call = () => collection.AddRange(modelsToAdd, "valid/file/path");
 
             // Assert
-            string message = $"Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele namen: {someName}.";
+            string message = $"Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele elementen: {someName}.";
             TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(call, message);
         }
 
@@ -100,7 +100,7 @@
             TestDelegate call = () => collection.AddRange(modelsToAdd, "valid/file/path");
 
             // Assert
-            string message = $"Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele namen: {someName}, {someOtherName}.";
+            string message = $"Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele elementen: {someName}, {someOtherName}.";
             TestHelper.AssertThrowsArgumentExceptionAndTestMessage<ArgumentException>(call, message);
         }
     }
Index: Ringtoets/Piping/test/Ringtoets.Piping.Data.TestUtil.Test/TestPipingFailureMechanismTest.cs
===================================================================
diff -u -rbdc32ff91af686a45b08e5f4f4a8d5b45eaba60f -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/test/Ringtoets.Piping.Data.TestUtil.Test/TestPipingFailureMechanismTest.cs	(.../TestPipingFailureMechanismTest.cs)	(revision bdc32ff91af686a45b08e5f4f4a8d5b45eaba60f)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Data.TestUtil.Test/TestPipingFailureMechanismTest.cs	(.../TestPipingFailureMechanismTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -52,7 +52,7 @@
             // Assert
             Assert.AreEqual(24, failureMechanism.Contribution);
 
-            ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine> surfaceLines = failureMechanism.SurfaceLines;
+            ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine> surfaceLines = failureMechanism.SurfaceLines;
             Assert.AreEqual("path/to/surfaceLines", surfaceLines.SourcePath);
             Assert.AreEqual(1, surfaceLines.Count);
             RingtoetsPipingSurfaceLine[] surfaceLineArray = surfaceLines.ToArray();
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/RingtoetsPipingSurfaceLineCollectionPropertiesTest.cs
===================================================================
diff -u -r580a0557ffdf6af30593c7a94c561b353a0400cb -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/RingtoetsPipingSurfaceLineCollectionPropertiesTest.cs	(.../RingtoetsPipingSurfaceLineCollectionPropertiesTest.cs)	(revision 580a0557ffdf6af30593c7a94c561b353a0400cb)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/RingtoetsPipingSurfaceLineCollectionPropertiesTest.cs	(.../RingtoetsPipingSurfaceLineCollectionPropertiesTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -50,14 +50,14 @@
         {
             // Setup
             var someFilePath = "location/to/a/file";
-            var collection = new ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine>();
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine>();
             collection.AddRange(Enumerable.Empty<RingtoetsPipingSurfaceLine>(), someFilePath);
 
             // Call
             var properties = new RingtoetsPipingSurfaceLineCollectionProperties(collection);
 
             // Assert
-            Assert.IsInstanceOf<ObjectProperties<ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine>>>(properties);
+            Assert.IsInstanceOf<ObjectProperties<ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine>>>(properties);
             Assert.AreSame(collection, properties.Data);
             Assert.AreEqual(someFilePath, properties.SourcePath);
         }
@@ -66,7 +66,7 @@
         public void Constructor_WithData_PropertiesHaveExpectedAttributesValues()
         {
             // Setup
-            var collection = new ObservableCollectionWithSourcePath<RingtoetsPipingSurfaceLine>();
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<RingtoetsPipingSurfaceLine>();
 
             // Call
             var properties = new RingtoetsPipingSurfaceLineCollectionProperties(collection);
Index: Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/StochasticSoilModelCollectionPropertiesTest.cs
===================================================================
diff -u -r5ad23eae9f87bb12cbf453126070e8967e32d7ad -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/StochasticSoilModelCollectionPropertiesTest.cs	(.../StochasticSoilModelCollectionPropertiesTest.cs)	(revision 5ad23eae9f87bb12cbf453126070e8967e32d7ad)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Forms.Test/PropertyClasses/StochasticSoilModelCollectionPropertiesTest.cs	(.../StochasticSoilModelCollectionPropertiesTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -50,14 +50,14 @@
         {
             // Setup
             var someFilePath = "location/to/a/file";
-            var collection = new ObservableCollectionWithSourcePath<StochasticSoilModel>();
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel>();
             collection.AddRange(Enumerable.Empty<StochasticSoilModel>(), someFilePath);
 
             // Call
             var properties = new StochasticSoilModelCollectionProperties(collection);
 
             // Assert
-            Assert.IsInstanceOf<ObjectProperties<ObservableCollectionWithSourcePath<StochasticSoilModel>>>(properties);
+            Assert.IsInstanceOf<ObjectProperties<ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel>>>(properties);
             Assert.AreSame(collection, properties.Data);
             Assert.AreEqual(someFilePath, properties.SourcePath);
         }
@@ -66,7 +66,7 @@
         public void Constructor_WithData_PropertiesHaveExpectedAttributesValues()
         {
             // Setup
-            var collection = new ObservableCollectionWithSourcePath<StochasticSoilModel>();
+            var collection = new ObservableUniqueItemCollectionWithSourcePath<StochasticSoilModel>();
 
             // Call
             var properties = new StochasticSoilModelCollectionProperties(collection);
Index: Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/RingtoetsPipingSurfaceLineReplaceDataStrategyTest.cs
===================================================================
diff -u -r036199c1cde97f98829dc4405169ec327d2a1b95 -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/RingtoetsPipingSurfaceLineReplaceDataStrategyTest.cs	(.../RingtoetsPipingSurfaceLineReplaceDataStrategyTest.cs)	(revision 036199c1cde97f98829dc4405169ec327d2a1b95)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/RingtoetsPipingSurfaceLineReplaceDataStrategyTest.cs	(.../RingtoetsPipingSurfaceLineReplaceDataStrategyTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -265,7 +265,7 @@
 
             // Assert
             var exception = Assert.Throws<RingtoetsPipingSurfaceLineUpdateException>(call);
-            string expectedMessage = $"Profielschematisaties moeten een unieke naam hebben. Gevonden dubbele namen: {duplicateName}.";
+            string expectedMessage = $"Profielschematisaties moeten een unieke naam hebben. Gevonden dubbele elementen: {duplicateName}.";
             Assert.AreEqual(expectedMessage, exception.Message);
             Assert.IsInstanceOf<ArgumentException>(exception.InnerException);
         }
Index: Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/StochasticSoilModelReplaceDataStrategyTest.cs
===================================================================
diff -u -re1a8e98d60853beefbdb8c84e70f14165680ad7b -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/StochasticSoilModelReplaceDataStrategyTest.cs	(.../StochasticSoilModelReplaceDataStrategyTest.cs)	(revision e1a8e98d60853beefbdb8c84e70f14165680ad7b)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/StochasticSoilModelReplaceDataStrategyTest.cs	(.../StochasticSoilModelReplaceDataStrategyTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -225,7 +225,7 @@
 
             // Assert
             var exception = Assert.Throws<StochasticSoilModelUpdateException>(test);
-            Assert.AreEqual("Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele namen: B.", exception.Message);
+            Assert.AreEqual("Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele elementen: B.", exception.Message);
             Assert.IsInstanceOf<ArgumentException>(exception.InnerException);
         }
     }
Index: Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/StochasticSoilModelUpdateDataStrategyTest.cs
===================================================================
diff -u -re1a8e98d60853beefbdb8c84e70f14165680ad7b -r66b07e7599319ea71ff109d8303f74a4a2e5f71c
--- Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/StochasticSoilModelUpdateDataStrategyTest.cs	(.../StochasticSoilModelUpdateDataStrategyTest.cs)	(revision e1a8e98d60853beefbdb8c84e70f14165680ad7b)
+++ Ringtoets/Piping/test/Ringtoets.Piping.Plugin.Test/FileImporter/StochasticSoilModelUpdateDataStrategyTest.cs	(.../StochasticSoilModelUpdateDataStrategyTest.cs)	(revision 66b07e7599319ea71ff109d8303f74a4a2e5f71c)
@@ -149,7 +149,7 @@
 
             // Assert
             var exception = Assert.Throws<StochasticSoilModelUpdateException>(test);
-            Assert.AreEqual("Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele namen: non-unique name.", exception.Message);
+            Assert.AreEqual("Ondergrondmodellen moeten een unieke naam hebben. Gevonden dubbele elementen: non-unique name.", exception.Message);
             Assert.IsInstanceOf<ArgumentException>(exception.InnerException);
         }